Methods for Optical System Manufacturing

ABSTRACT

Systems and methods described herein relate to the manufacture of optical elements and optical systems. An example method includes providing a first substrate that has a plurality of light-emitter devices disposed on a first surface. The method includes providing a second substrate that has a mounting surface defining a reference plane. The method includes forming a structure and an optical spacer on the mounting surface of the second substrate. The method additionally includes coupling the first and second substrates together such that the first surface of the first substrate faces the mounting surface of the second substrate at an angle with respect to the reference plane.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 17/234,960,filed Apr. 20, 2021, which is a continuation of application Ser. No.16/705,406, filed Dec. 6, 2019, which is a continuation of applicationSer. No. 16/136,429, filed Sep. 20, 2018. The foregoing applications areincorporated herein by reference.

BACKGROUND

Unless otherwise indicated herein, the materials described in thissection are not prior art to the claims in this application and are notadmitted to be prior art by inclusion in this section,

Achieving and maintaining proper alignment between optical components ina complex optical system can represent a formidable manufacturingchallenge. For example, some optical systems include parts that shouldbe arranged according to placement tolerances that can be 50 microns, 10microns, or even less.

SUMMARY

Systems and methods described herein are applicable to the manufactureof optical systems. For example, the present disclosure describescertain optical components (e.g., light guide devices and opticallenses) and methods of their manufacture to provide an optical system.

In a first aspect, a method for manufacturing an optical system isprovided. The method includes providing a first substrate. The firstsubstrate has a first surface and a second surface opposite the firstsurface. A plurality of light-emitter devices is disposed on the firstsurface. The method includes providing a second substrate. The secondsubstrate has a mounting surface that defines a reference plane. Themethod additionally includes forming a structure and an optical spaceron the mounting surface of the second substrate. The method furtherincludes coupling at least one spacer to the mounting surface of thesecond substrate. The method yet further includes coupling at least onecylindrical lens to the mounting surface of the second substrate. Themethod includes coupling the first and second substrates together suchthat a first portion of the first substrate is coupled to the mountingsurface of the second substrate and a second portion of the firstsubstrate is coupled to the optical spacer formed on the mountingsurface of the second substrate and the first surface of the firstsubstrate faces the mounting surface of the second substrate at an anglewith respect to the reference plane.

In a second aspect, an optical system is provided. The optical systemincludes a first substrate. The first substrate has a first surface anda second surface opposite the first surface. A plurality oflight-emitter devices is disposed on the first surface. The opticalsystem also includes a second substrate. The second substrate has amounting surface that defines a reference plane. The second substrateincludes a structure and an optical spacer on the mounting surface, atleast one spacer coupled to the mounting surface, and at least onecylindrical lens coupled to the mounting surface. The first substrateand the second substrate are coupled together such that a first portionof the first substrate is coupled to the optical spacer on the mountingsurface of the second substrate and the first surface of the firstsubstrate faces the mounting surface of the second substrate at an anglewith respect to the reference plane.

Other aspects, embodiments, and implementations will become apparent tothose of ordinary skill in the art by reading the following detaileddescription, with reference where appropriate to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of an optical system, according to anexample embodiment.

FIG. 2 illustrates an optical system, according to an exampleembodiment.

FIG. 3A illustrates a step of a method of manufacture, according to anexample embodiment.

FIG. 3B illustrates a step of a method of manufacture, according to anexample embodiment.

FIG. 3C illustrates a step of a method of manufacture, according to anexample embodiment.

FIG. 3D illustrates a step of a method of manufacture, according to anexample embodiment.

FIG. 3E illustrates a step of a method of manufacture, according to anexample embodiment.

FIG. 3F illustrates a step of a method of manufacture, according to anexample embodiment.

FIG. 3G illustrates a step of a method of manufacture, according to anexample embodiment.

FIG. 4 illustrates a method, according to an example embodiment.

DETAILED DESCRIPTION

Example methods, devices, and systems are described herein. It should beunderstood that the words “example” and “exemplary” are used herein tomean “serving as an example, instance, or illustration.” Any embodimentor feature described herein as being an “example” or “exemplary” is notnecessarily to be construed as preferred or advantageous over otherembodiments or features. Other embodiments can be utilized, and otherchanges can be made, without departing from the scope of the subjectmatter presented herein.

Thus, the example embodiments described herein are not meant to belimiting. Aspects of the present disclosure, as generally describedherein, and illustrated in the figures, can be arranged, substituted,combined, separated, and designed in a wide variety of differentconfigurations, all of which are contemplated herein.

Further, unless context suggests otherwise, the features illustrated ineach of the figures may be used in combination with one another. Thus,the figures should be generally viewed as component aspects of one ormore overall embodiments, with the understanding that not allillustrated features are necessary for each embodiment.

I. Overview

The present disclosure provides systems and methods for manufacturing anoptical system that can beneficially provide reliable and repeatablealignment of a plurality of light-emitters with a correspondingplurality of optical lenses and light guide manifolds (e.g., waveguidesand/or light pipes).

An example method includes providing a first substrate, which couldinclude a printed circuit board material (e.g., FR-4) and/or a flexibleprinted circuit board material. In some embodiments, the first substratecould be approximately 200 microns thick. The first substrate includes aplurality of light-emitter devices, which could be arranged along asurface of the first substrate. In some examples, the method may includecausing a die bonder to place the plurality of light-emitter devices onthe first substrate. In some embodiments, the first substrate couldadditionally include a plurality of spring structures. In suchscenarios, the spring structures could include the loops of wire bondsprovided on the surface of the first substrate. Additionally oralternatively, the spring structures could include a soft material, suchas a polymer (e.g., silicone) or another similar material. The springstructures could include, without limitation, one or more elasticmaterials configured to exert a restoring force in response to beingdeformed (e.g., compressed).

The method also includes providing a second substrate. In an exampleembodiment, the second substrate could include glass, although othermaterials are possible. In some embodiments, a surface of the secondsubstrate could be very flat so as to provide a topographic referenceplane.

The method includes forming a raised portion on the second substrate. Asan example, the raised portion could includephotolithographically-defined materials such as SU-8, PMMA, etc. Otheradditive and/or subtractive manufacturing methods are contemplated toform the raised portion. In some embodiments, the raised portion couldbe about 400 microns tall with respect to the topographic referenceplane, however other height values for the raised portion are possibleand contemplated. The raised portion could be an optical component, suchas a light guide manifold.

Additionally, the method includes fixing at least one spacer and atleast one cylindrical lens to the second substrate. In an exampleembodiment, the second substrate includes a plurality ofthree-dimensional alignment structures (e.g., grippers) that can be usedto help position the spacer and the cylindrical lens. In some examples,such alignment structures could be formed withphotolithographically-defined materials (e.g., SU-8, PMMA, etc.) or asprotrusions/recesses etched onto the second substrate (glass wafer).

In some embodiments, the spacers and the cylindrical lenses could beformed from drawn optical fibers. Accordingly, the spacers andcylindrical lenses could include materials such as glass (silica),polycarbonate, polyethylene, fluoride, chalcogenides, and/or otheroptical materials. In some embodiments, the material for the spacer andcylindrical lens could be different. For example, because the spacer isnot utilized for its optical properties, as such the spacer need not bean optical material at all.

In an example embodiment, the cylindrical lenses could be about 125microns in diameter and the spacers could be about 50 microns indiameter, although other sizes are possible and contemplated. A benefitto using a drawn fiber for the spacer is that it may have a uniformdiameter along its length within a very tight manufacturing tolerance(e.g., 1-10 micron variation, or less).

In example embodiments, the method may include applying an adhesivematerial to the first substrate and/or the second substrate. In somescenarios, the adhesive material could include an optical epoxy, aUV-curable epoxy, and/or a thermally-curable adhesive. Other types ofadhesive materials (e.g., tape films) are contemplated. The adhesivematerial could be applied at regions that are relatively distant fromthe light-emitter devices, spacer, cylindrical lens, and/or light guidemanifold.

The method includes aligning the first substrate to the secondsubstrate. This alignment step could include two cameras that arearranged to view the first and second substrates through a backsidesurface of the transparent or translucent second substrate. A firstcamera could be arranged to view a first set of alignment features onthe first and/or the second substrates and the second camera could bearranged to view a second set of alignment features on the firstsubstrate and/or second substrate. In some embodiments, the first andsecond sets of alignment features could be spaced widely apart along thefirst and/or second substrate (near the extents of one or bothsubstrates) so as to more easily detect, and correct for, misalignment.

In some embodiments, a vacuum could be applied to the first substrate,for example, using a vacuum chuck, to hold the first substrate in adesired position. In such scenarios, the vacuum chuck could be attachedto a positioning stage configured to adjust a position of the firstsubstrate with respect to the second substrate according to a desiredproper alignment. As such, the alignment step could include causing thepositioning stage to adjust a position of the first substrate so as toalign the first and second substrates. For example, an alignment toolcould be compliant and/or adjustable about the two axes that are in thesubstrate plane (e.g., tip/tilt in the x and y axes), but non-compliantwith regard to translational motion in x and y directions and rotationalmotion in the z axis. Additionally or alternatively, such an alignmenttool could measure the relative angular and/or translational position ofthe first and second substrates and actively rotate one or both of themuntil they are parallel and translationally aligned.

In some embodiments, proper alignment between the first and the secondsubstrates could involve a surface of the light-emitter device beingpositioned to physically contact the spacer. Furthermore, thelight-emitter device could be positioned so as to emit light toward thecylindrical lens. In some embodiments, the cylindrical lens couldprovide a fast-axis collimation for light emitted by the light-emitterdevice.

In embodiments that include spring structures (e.g., wire bond loops ora soft polymer material) on the first substrate, proper alignment couldalso include the spring structures being positioned to physicallycontact the cylindrical lens on the second substrate.

Once the first and second substrates are aligned, the method includescausing the positioning stage to bring the first substrate in physicalcontact with the second substrate. In some embodiments, the firstsubstrate could contact the second substrate such that the firstsubstrate forms a “bridge” from a location along the topographicalreference plane on the second substrate to a location along the raisedportion on the second substrate. For example, when in contact with thesecond substrate, the first substrate could be angled at an approximate2 degrees incline with respect to the second substrate.

In such scenarios, the positioning stage may apply, and maintain, apredetermined contact force between the first substrate and the secondsubstrate. In some examples, the predetermined contact force could bebetween 10 Newtons to 100 Newtons. In some embodiments, an initialalignment contact force (e.g., 10 Newtons) could be maintained duringthe alignment process. Once alignment is achieved, a higher contactforce (e.g., 60 Newtons) could be applied during the curing of theadhesive material.

In some embodiments, the contact force could be provided, at least inpart, by physical contact between one or more of the following: 1) thelight-emitter device on the first substrate being in contact with thespacer on the second substrate; 2) a spring structure on the firstsubstrate being in contact with the cylindrical lens on the secondsubstrate; and 3) a first portion of the first substrate (e.g., a firstend of the first substrate) being in contact with the topographicreference plane and a second portion of the first substrate (e.g., asecond end of the first substrate, opposite the first end) being incontact with the raised portion of the second substrate.

In some embodiments, information indicative of the contact force may beprovided by one or more strain gauges that could be coupled to thevacuum chuck and/or the positioning stage. In such scenarios, the straingauges could include one or more load cells (e.g., shear-type,compression-type, loadpin, etc.). The method could include adjusting thepositioning stage based on the information provided by the strain gaugesso as to achieve and/or maintain the predetermined contact force.Additionally or alternatively, the method could include using the straingauge information to establish and/or maintain co-planarity of the firstand second substrates.

In some embodiments, the method includes, while the predeterminedcontact force (e.g., 60 Newton) is being maintained, curing the adhesivematerial so as to permanently bond the first and second substrates. Forexample, a UV light could be applied to cure UV-curable epoxy.Additionally or alternatively, heat could be applied (e.g., with aheated chuck), so as to cure thermally-curable adhesive materials.

In some embodiments, the method could include “pre-bending” the firstsubstrate so as to reduce peeling forces that may act to delaminate thefirst substrate from the second substrate. For example, a pre-bendingprocess could plastically deform the first substrate so as to reducesuch peeling forces when the first substrate is subsequently bonded tothe second substrate.

II. Example Optical Systems

FIG. 1 illustrates a block diagram of an optical system 100, accordingto an example embodiment. Optical system 100 could be utilized invarious compact LIDAR systems. Such LIDAR systems may be configured toprovide information (e.g., point cloud data) about one or more objects(e.g., location, shape, etc.) in a given environment. In an exampleembodiment, the LIDAR system could provide point cloud information,object information, mapping information, or other information to avehicle. The vehicle could be a semi- or fully-automated vehicle. Forinstance, the vehicle could be a self-driving car, an autonomous droneaircraft, an autonomous truck, or an autonomous robot. Other types ofvehicles and LIDAR systems are contemplated herein.

The optical system 100 includes a first substrate 110, which has a firstsurface 112 and a second surface 114 opposite the first surface 112. Insome embodiments, the first substrate 110 is a printed circuit board(PCB). However, the first substrate 110 could be formed from a varietyof different materials, each of which is contemplated in the presentdisclosure. In some examples, the first substrate 110 could beapproximately 200 microns thick. However, other thicknesses are possibleand contemplated.

In various embodiments, the first substrate 110 includes a plurality ofspring structures 160 on the first surface 112 of the first substrate110. The spring structures 160 could provide a compliant, spring-likeforce in a direction normal to the surface of the first substrate 110.In some cases, the plurality of spring structures 160 could include aplurality of looped wire bonds and/or a soft polymer material. Othertypes of springs and/or spring-like structures are contemplated herein.

A plurality of light-emitter devices 120 is disposed on the firstsurface 112 of the first substrate 110. The plurality of light-emitterdevices 120 could be configured to provide light pulses in infraredwavelengths (e.g., 905 nm). Other wavelengths and wavelength ranges arepossible and contemplated. The plurality light-emitter devices 120 couldeach include one or more laser bars or another type of light-emittingstructure. In some embodiments, control circuitry (e.g., pulsercircuits) for the plurality of light-emitter devices 120 could also bedisposed along the first surface 112 of the first substrate 110. Inother embodiments, the control circuitry could be located elsewhere.

The optical system 100 also includes a second substrate 130 that has amounting surface 132 that defines a reference plane. The secondsubstrate 130 also includes a structure 136 and an optical spacer 137 onthe mounting surface 132. In some cases, the structure 136 may be formedfrom a polymeric material, such as photoresist. For example, thepolymeric material may include SU-8 polymer, Kloe K-CL negativephotoresist, Dow PHOTOPOSIT negative photoresist, or JSR negative toneTHB photoresist. It will be understood that the structure 136 may beformed from other polymeric photo-patternable materials. The structure136 could be a photo-patterned material layer that is 400 microns thick.However, the structure 136 could be a different thickness.

The structure 136 may include an optical waveguide configured toefficiently guide light along a propagation direction. For example, thestructure 136 may be configured to couple light emitted from theplurality of light-emitter devices 120. At least a portion of such lightmay be guided within at least a portion of the structure 136 via totalinternal reflection. In some embodiments, the structure 136 may includeone or more reflective surfaces configured to direct light normal to thepropagation direction. In such a scenario, at least a portion of thelight may be coupled out of the structure 136 via a mirrored facet.

In some embodiments, the optical spacer 137 could be provided to improveoptical isolation between the structure 136 and the first substrate 110and/or to preserve the light guiding properties of the structure 136.For instance, in some scenarios, the optical spacer 137 could include apartially-etched stainless steel spacer that forms a “tunnel” or air gaparound the structure 136. In other words, such an optical spacer 137could be directly “sandwiched” between the first substrate 110 and thesecond substrate 130 in the region of the structure 136. That is, air—oranother material with a low refractive index with respect to that of thestructure 136—could surround at least a portion of the structure 136. Insuch scenarios, the structure 136 need not be directly coupled to thefirst substrate 110, but rather could be indirectly coupled to the firstsubstrate 110 by way of the optical spacer 137.

Put another way, in some embodiments, the optical spacer 137 may providea “scaffolding” around the structure 136 so as to prevent the firstsubstrate 110 from physically touching the structure 136. The opticalspacer 137 could be formed from copper, stainless steel, or anickel—cobalt ferrous alloy such as Kovar. Additionally oralternatively, the material of the optical spacer 137 could be selectedbased on its coefficient of thermal expansion (CTE). Specifically, theoptical spacer 137 could be formed from a material that has a CTEsimilar (e.g., within 10% or 1%) to that of the second substrate 130.

The second substrate 130 includes at least one spacer 140 coupled to themounting surface 132. In some embodiments, the at least one spacer 140could be cylindrical with a diameter between 40-60 microns. However,other diameters or shapes for the at least one spacer 140 are possibleand contemplated. In some embodiments, the at least one spacer 140 couldbe coupled to the mounting surface 132 with epoxy or another type ofadhesive. Additionally or alternatively, the at least one spacer 140could be disposed between at least one pair of guide structures. The atleast one pair of guide structures could be configured to secure the atleast one spacer 140 from moving away to a predetermined location.

The second substrate 130 also includes at least one cylindrical lens 150(or other shaped lens) coupled to the mounting surface 132. In someembodiments, the at least one cylindrical lens 150 could be coupled tothe mounting surface 132 with epoxy or another type of adhesive.Additionally or alternatively, the at least one cylindrical lens 150could be disposed between at least one pair of guide structures. The atleast one pair of guide structures could be configured to secure the atleast one cylindrical lens 150 to a predetermined location. In anexample embodiment, the cylindrical lens 150 could be utilized to focus,defocus, direct, and/or otherwise couple the emitted light into thestructure 136. In some embodiments, the cylindrical lens 150 could beapproximately 100-200 microns in diameter. However, other diameters arepossible and contemplated. In addition, lenses that are in other shapescould be used instead of or in addition to the at least one cylindricallens 150.

The first substrate 110 and the second substrate 130 are coupledtogether such that a first portion 116 of the first substrate 110 iscoupled to the optical spacer 137 on the mounting surface 132 of thesecond substrate 130. The first surface 112 of the first substrate 110faces the mounting surface 132 of the second substrate 130 at an anglewith respect to the reference plane.

In some embodiments, the at least one spacer 140 and/or the at least onecylindrical lens 150 could include an optical fiber. In otherembodiments, the at least one spacer 140 and/or the at least onecylindrical lens 150 could include materials such as glass (silica),polycarbonate, polyethylene, fluoride, chalcogenides, and/or otheroptical materials. In yet other embodiments, the at least one spacer 140need not be an optical material at all. In such scenarios, the at leastone spacer 140 could be formed from silicon, ceramic, or anotheroptically opaque material.

In some embodiments, the first substrate 110 includes a plurality ofspring structures 160 on the first surface 112 of the first substrate110. The first substrate 110 and the second substrate 130 are coupledtogether such that: a) at least one light-emitter device of theplurality of light-emitter devices 120 is in physical contact with theat least one spacer 140; and b) at least one spring structure of theplurality of spring structures 160 is in physical contact with the atleast one cylindrical lens 150.

FIG. 2 illustrates a side view and close-up side view of optical system200, according to an example embodiment. Optical system 200 could besimilar or identical to optical system 100, as illustrated and describedin reference to FIG. 1 . For example, optical system 200 includes afirst substrate 110 and a second substrate 130. A plurality oflight-emitter devices 120 are coupled to a first surface 112 of thefirst substrate 110. While FIG. 2 illustrates a single light-emitterdevice 120, in some embodiments, the light-emitter device 120 couldinclude a plurality of light-emitter devices (e.g., 256 or more laserbars). In an example embodiment, the plurality of light-emitter devicescould extend “into the page” along the y-axis.

In some embodiments, a plurality of spring structures 160 could becoupled to the first surface 112 of the first substrate 110. While FIG.2 illustrates a single spring structure 160, in some embodiments, theoptical system 200 could include a plurality of spring structures (e.g.,10, 50, 100, or more spring structures). In an example embodiment, theplurality of spring structures 160 could extend “into the page” alongthe y-axis.

The second substrate 130 has a mounting surface 132 upon which ismounted a spacer 140, a cylindrical lens 150, a structure 136, and anoptical spacer 137. In an example embodiment, the cylindrical lens 150could be disposed along the mounting surface 132 and between the spacer140 and the structure 136. The spacer 140 and the cylindrical lens 150could be cylindrically-shaped and extend along the y-axis as illustratedin FIG. 2 . However, other shapes and arrangements of the spacer 140,cylindrical lens 150, structure 136, and optical spacer 137 are possibleand contemplated. In some embodiments, the second substrate 130 could bepartially transparent. As an example, the second substrate 130 could beglass or another material that is substantially optically-transparent inthe visible wavelengths.

The first substrate 110 is coupled to the second substrate 130 at leastat two locations: 1) a first portion 116 of the first substrate 110could be coupled to the mounting surface 132 of the second substrate130; and 2) a second portion 118 of the first substrate 110 could becoupled to the optical spacer 137 on the second substrate 130. In such ascenario, the first surface 112 of the first substrate 110 faces themounting surface 132.

In some embodiments, coupling the first substrate 110 to the secondsubstrate 130 could include bonding the two substrates using an epoxy oranother optical adhesive material. Coupling the first substrate 110 andthe second substrate 130 as illustrated in FIG. 2 could cause a topsurface 222 of the at least one light-emitter device 120 to physicallycontact the spacer 140. As such, the spacer 140 could be configured toact as a “land” or stop for the light-emitter device 120 in thez-direction. That is, the spacer 140 could control the z-height of thelight-emitter device 120 when the first substrate 110 is coupled to thesecond substrate 130.

The light-emitter device 120 could include an epitaxially-grown laserdiode region 224. The laser diode region 224 could include semiconductormaterial from which photons are emitted with a particular emissionpattern. By controlling the z-height of the light-emitter device 120,the location of the emission pattern 226 of the epitaxially-grown laserdiode region 224 can be positioned so as to interact with thecylindrical lens 150.

Additionally, coupling the first substrate 110 to the second substrate130 could cause a spring structure 160 to physically contact thecylindrical lens 150. That is, at least a portion of the springstructure 160 could push downward (in the -z direction) onto an outersurface of the cylindrical lens 150. In so doing, the spring structure160 could help retain and/or position the cylindrical lens 150 at adesired location.

III. Example Methods

FIGS. 3A-3G illustrate various steps of a method of manufacture,according to one or more example embodiments. It will be understood thatat least some of the various steps may be carried out in a differentorder than of that presented herein. Furthermore, steps may be added,subtracted, transposed, and/or repeated. FIGS. 3A-3G may serve asexample illustrations for at least some of the steps or stages describedin relation to method 400 as illustrated and described in relation toFIG. 4 . Additionally, some steps of FIGS. 3A-3G may be carried out soas to provide optical system 100, as illustrated and described inreference to FIGS. 1 and 2 .

FIG. 3A illustrates a step of a method of manufacture 300, according toan example embodiment. Step 300 includes providing a first substrate110. As illustrated, a first substrate 110 could include a first surface112 and a second surface 114. A plurality of light-emitter devices 120could be disposed on the first surface 112. The plurality oflight-emitter devices 120 could extend along the y-axis. In someembodiments, an epitaxially-grown laser diode region 224 could belocated a known distance below a top surface 222 of the light-emitterdevices 120. A plurality of spring structures 160 could be placed on thefirst surface 112. For example, the spring structures 160 could includewire bonds applied to the first surface 112 using a wire bonder.Additionally or alternatively, the spring structures 160 could include asoft polymer material, which could be applied with a pipette, a syringe,or another type of applicator.

FIG. 3B illustrates a step of a method of manufacture 310, according toan example embodiment. Step 310 includes providing a second substrate130. The second substrate 130 includes a mounting surface 132 and abackside surface 234. In some embodiments, the second substrate 130 maybe partially or completely transparent. For instance, the secondsubstrate 130 could be formed from glass or another material that issubstantially transparent to visible light.

FIG. 3C illustrates a step of a method of manufacture 320, according toan example embodiment. Step 320 includes forming a structure 136 andoptical spacer 137 on the mounting surface 132. In some embodiments,forming the structure 136 could include one or more photolithographyexposures to define a photo-definable resist material. In someembodiments, the structure 136 could be an optical waveguide configuredto guide light via, e.g., total internal reflection. As describedelsewhere herein, the optical spacer 137 could include a stainless steel“scaffolding” to maintain an air gap around the structure 136.

FIG. 3D illustrates a step of a method of manufacture 330, according toan example embodiment. Step 330 includes coupling a spacer 140 to themounting surface 132 of the second substrate 130. In some embodiments,coupling the spacer 140 to the mounting surface 132 could include usinga pick-and-place system to position the spacer 140 in a desired locationalong the mounting surface 132. Additionally or alternatively, thespacer 140 could be coupled to the mounting surface 132 using epoxy oranother adhesive material.

In some embodiments, three-dimensional alignment structures 142 could beapplied to the mounting surface before or after the spacer 140 ispositioned along the mounting surface 132. The alignment structures 142could help to properly position the spacer 140 and/or help maintain itsposition. In some cases, the alignment structures 142 could bepositioned to form a slot for the spacer 140. In other words, thealignment structures 142 could grip the spacer 140 so as to affix orfasten it in place. The alignment structures 142 could be defined usingphotolithography. For example, the alignment structures 142 could beformed with a photo-definable material.

FIG. 3E illustrates a step of a method of manufacture 340, according toan example embodiment. Step 340 includes coupling a cylindrical lens 150to the mounting surface 132 of the second substrate 130. In someembodiments, coupling the cylindrical lens 150 to the mounting surface132 could include using a pick-and-place system to position thecylindrical lens 150 in a desired location along the mounting surface132. Additionally or alternatively, the cylindrical lens 150 could becoupled to the mounting surface 132 using epoxy or another adhesivematerial.

In some embodiments, three-dimensional alignment structures 152 could beapplied to the mounting surface before or after the cylindrical lens 150is positioned along the mounting surface 132. The alignment structures152 could help to properly position the cylindrical lens 150 and/or helpmaintain its position. In some cases, the alignment structures 152 couldbe positioned to form a slot for the cylindrical lens 150. In otherwords, the alignment structures 152 could grip the cylindrical lens 150so as to affix or fasten it in place. The alignment structures 152 couldbe defined using photolithography. For example, the alignment structures152 could be formed with a photo-definable material.

FIG. 3F illustrates a step of a method of manufacture 350, according toan example embodiment. Step 350 includes the first substrate 110 beingcoupled to the second substrate 130. Namely, a first portion 116 of thefirst substrate 110 is coupled to the mounting surface 132 of the secondsubstrate 130 and a second portion 118 of the first substrate 110 iscoupled to the optical spacer 137. In so doing, the first surface 112 ofthe first substrate 110 faces the mounting surface 132.

When coupling the first substrate 110 to the second substrate 130, theplurality of light-emitter devices 120 could come into physical contactwith the spacer 140. That is, a respective top surface 222 of theplurality of light-emitter devices 120 could push against the spacer140. Furthermore, as a result of coupling the first substrate 110 andthe second substrate 130, the cylindrical lens 150 could come intophysical contact with the spring structures 160. Namely, in someembodiments, the spring structures 160 may bend so as to compliantlyprovide a force to a surface of the cylindrical lens 150. In thisarrangement, an epitaxially-grown laser diode region 224 could bepositioned with respect to the cylindrical lens 150 such that the laserdiode region 224 emits light that is fast-axis collimated by thecylindrical lens 150.

In some embodiments, the first substrate 110 may bend due to one or morephysical forces exerted upon it. For example, the first surface 112 andthe second surface 114 could be bent with respect to a pre-couplingcondition of the first substrate 110. That is, prior to coupling thefirst substrate 110 to the second substrate 130, the first substrate 110may be substantially planar. However, after coupling the first substrate110 to the second substrate 130, at least a portion of the firstsubstrate 110 may bend to balance the forces exerted upon the topsurface 222 of the light-emitter device 120 by the spacer 140 and/or theforces exerted upon the cylindrical lens 150 by the spring structure160, and vice versa.

In some examples, the first substrate 110 may be “pre-bent” prior tocoupling it with the second substrate 130. In such a scenario, the firstsubstrate 110 could be plastically deformed with heat and/or pressure soas to more compliantly couple with the second substrate 130. Forexample, the first portion 116 of the first substrate 110 and the secondportion 118 of the first substrate 110 could be pre-bent so as to reducedelamination issues after coupling with the second substrate 130. Other“pre-bending” steps are contemplated so as to reduce or eliminatephysical stresses on the first substrate 110, the second substrate 130,and/or other components of the optical system 100.

FIG. 3G illustrates a step of a method of manufacture 360, according toan example embodiment. Step 360 could include causing the plurality oflight-emitter devices 120 to emit light according to an emission pattern362. At least a portion of the emission pattern 362 could interact withthe cylindrical lens 150. In such a scenario, the focused light 364could be coupled into the structure 136 and be propagated within thestructure 136 along the x-direction as guided light 366. The guidedlight 366 could be imaged elsewhere in the optical system using, forexample, one or more photodetectors (e.g., a camera). Step 360 could beutilized, for example, as a calibration step during manufacturing orperiodically during normal operation to check proper alignment of thecomponents of the optical system 100. By way of example, alignment ofthe optical system 100 could be checked/maintained with automatedoptical inspection (AOI) techniques. For example, AOI could confirmalignment of the first and second substrates by checking fiducial marks,optical vernier marks, or other types of alignment indicators. In somecases, the AOI could include observing such marks by imaging through atransparent portion of the second substrate 130.

FIG. 4 illustrates a method 400, according to an example embodiment.Method 400 may be carried out, at least in part, by way of some or allof the manufacturing steps or blocks illustrated and described inreference to FIGS. 3A-3G. It will be understood that the method 400 mayinclude fewer or more steps or blocks than those expressly disclosedherein. Furthermore, respective steps or blocks of method 400 may beperformed in any order and each step or block may be performed one ormore times. In some embodiments, method 400 and its steps or blocks maybe performed to provide an optical system that could be similar oridentical to optical system 100, as illustrated and described inreference to FIGS. 1 and 2 .

Block 402 includes providing a first substrate that has a first surfaceand a second surface opposite the first surface. In some examples, thefirst substrate could include a printed circuit board. However, othermaterials are contemplated. A plurality of light-emitter devices isdisposed on the first surface of the first substrate. As such, method400 could include using a pick-and-place system to position thelight-emitter devices on the first surface. In some scenarios, thelight-emitter devices could be bonded to the first surface with epoxy,an indium eutectic material, or another type of adhesive material.

Method 400 could additionally include electrically-connecting thelight-emitter devices to control circuitry (e.g., pulser circuits),which could be located on the first substrate or elsewhere. For example,electrically-connecting the light-emitter devices to their respectivecontrol circuits could include forming one or more wire bonds betweenthem using a wire or ribbon bonder system.

Block 404 includes providing a second substrate that has a mountingsurface defining a reference plane. The second substrate could includeat least one portion that is transparent so as to provide an alignmentwindow for aligning the second substrate with the first substrate asdescribed below.

Block 406 includes forming a structure and an optical spacer on themounting surface of the second substrate. In some embodiments, formingthe structure on the mounting surface of the second substrate comprisesperforming a photolithographic process to define the structure with aphotolithographically-definable material. In some embodiments, thestructure could include an optical waveguide that could be formed fromSU-8 or another optical material. As described elsewhere herein, theoptical spacer could be formed from stainless steel and could provide ascaffolding to maintain an air gap around the structure.

Block 408 includes coupling at least one spacer to the mounting surfaceof the second substrate. In some embodiments, coupling the at least onespacer to the mounting surface could include using a pick-and-placemachine to position the at least one spacer in the desired location onthe second substrate. As described elsewhere herein, the at least onespacer could include an optical fiber. However, other materials andshapes are possible and contemplated.

Block 410 includes coupling at least one cylindrical lens to themounting surface of the second substrate. In some embodiments, couplingthe at least one spacer or the at least one cylindrical lens to themounting surface of the second substrate could include coupling the atleast one spacer or the at least one cylindrical lens to a plurality ofthree-dimensional alignment structures on the mounting surface of thesecond substrate.

Block 412 includes coupling the first and second substrates togethersuch that a first portion of the first substrate is coupled to themounting surface of the second substrate and a second portion of thefirst substrate is coupled to the optical spacer formed on the mountingsurface of the second substrate and the first surface of the firstsubstrate faces the mounting surface of the second substrate at an anglewith respect to the reference plane.

In some embodiments, the structure formed on the mounting surface of thesecond substrate could be an optical waveguide. In such scenarios,coupling the first and second substrates together comprises opticallycoupling at least one light-emitter device of the plurality oflight-emitter devices to the optical waveguide via the at least onecylindrical lens.

In example embodiments, coupling the first and second substratestogether includes bringing at least one light-emitter device of theplurality of light-emitter devices into physical contact with the atleast one spacer.

In some embodiments, providing the first substrate could include forminga plurality of spring structures on the first surface of the firstsubstrate. In such scenarios, coupling the first and second substratestogether could include bringing at least one spring structure of theplurality of spring structures into physical contact with the at leastone cylindrical lens. In some cases, the plurality of spring structurescould include a plurality of looped wire bonds. That is, method 400could include the step of applying the plurality of looped wire bonds tothe first surface of the first substrate (e.g., with a wire bondingsystem).

Additionally or alternatively, the spring structures could include asoft polymer material. In such scenarios, the soft polymer materialcould be applied, by hand or with an automated system, using a pipette,a syringe, or another type of applicator.

In some embodiments, coupling the first and second substrates togethercould include applying an adhesive material to at least one of the firstportion of the first substrate or the mounting surface of the secondsubstrate. In such scenarios, the method 400 could include applying theadhesive material to at least one of the second portion of the firstsubstrate or the optical spacer formed on the mounting surface of thesecond substrate. Furthermore, method 400 could include curing theadhesive material such that the first portion of the first substrate isbonded to the mounting surface of the second substrate and the secondportion of the first substrate is bonded to the optical spacer formed onthe mounting surface of the second substrate.

Method 400 may include aligning the first substrate and the secondsubstrate with respect to one another before coupling the first andsecond substrates together. For instance, in some embodiments where thesecond substrate includes a transparent portion, aligning the firstsubstrate and the second substrate with respect to one another couldinclude imaging at least a portion of the first substrate through thetransparent portion of the second substrate. Furthermore, in suchscenarios, aligning the first substrate and the second substrate withrespect to one another may include adjusting a position of the firstsubstrate with respect to the second substrate to achieve a desiredalignment of the first and second substrates.

Additionally or optionally, coupling the first and second substratestogether could include applying a predetermined force (e.g., between 10Newtons to 100 Newtons) to the second surface of the first substrate.Other values of force are contemplated and possible.

The particular arrangements shown in the Figures should not be viewed aslimiting. It should be understood that other embodiments may includemore or less of each element shown in a given Figure. Further, some ofthe illustrated elements may be combined or omitted. Yet further, anillustrative embodiment may include elements that are not illustrated inthe Figures.

A step or block that represents a processing of information cancorrespond to circuitry that can be configured to perform the specificlogical functions of a herein-described method or technique.Alternatively or additionally, a step or block that represents aprocessing of information can correspond to a module, a segment, aphysical computer (e.g., a field programmable gate array (FPGA) orapplication-specific integrated circuit (ASIC)), or a portion of programcode (including related data). The program code can include one or moreinstructions executable by a processor for implementing specific logicalfunctions or actions in the method or technique. The program code and/orrelated data can be stored on any type of computer readable medium suchas a storage device including a disk, hard drive, or other storagemedium.

The computer readable medium can also include non-transitory computerreadable media such as computer-readable media that store data for shortperiods of time like register memory, processor cache, and random accessmemory (RAM). The computer readable media can also includenon-transitory computer readable media that store program code and/ordata for longer periods of time. Thus, the computer readable media mayinclude secondary or persistent long term storage, like read only memory(ROM), optical or magnetic disks, compact-disc read only memory(CD-ROM), for example. The computer readable media can also be any othervolatile or non-volatile storage systems. A computer readable medium canbe considered a computer readable storage medium, for example, or atangible storage device.

While various examples and embodiments have been disclosed, otherexamples and embodiments will be apparent to those skilled in the art.The various disclosed examples and embodiments are for purposes ofillustration and are not intended to be limiting, with the true scopebeing indicated by the following claims.

1-20. (canceled)
 21. An optical system, comprising: a first substrate,wherein the first substrate has a first surface and a second surfaceopposite the first surface; at least one light-emitter device disposedon the first surface of the first substrate; a second substrate, whereinthe second substrate has a mounting surface; a lens coupled to themounting surface of the second substrate; an optical waveguide disposedon the mounting surface of the second substrate; and a spacer coupled tothe mounting surface of the second substrate, wherein the spacer is inphysical contact with the at least one light-emitter device such thatthe at least one light-emitter device is optically coupled to theoptical waveguide via the lens.
 22. The optical system of claim 21,wherein the mounting surface of the second substrate defines a referenceplane, and wherein the first surface of the first substrate faces themounting surface of the second substrate at an angle with respect to thereference plane.
 23. The optical system of claim 21, further comprising:a plurality of three-dimensional alignment structures disposed on themounting surface of the second substrate, wherein the three-dimensionalalignment structures position the spacer and the lens on the mountingsurface.
 24. The optical system of claim 21, wherein the spacercomprises an optical fiber.
 25. The optical system of claim 21, whereinthe first substrate comprises a printed circuit board.
 26. The opticalsystem of claim 21, wherein at least a portion of the second substrateis transparent.
 27. The optical system of claim 26, wherein the secondsubstrate comprises glass.
 28. The optical system of claim 21, whereinthe lens is a cylindrical lens.
 29. The optical system of claim 28,wherein the cylindrical lens comprises an optical fiber.
 30. The opticalsystem of claim 21, wherein the at least one light-emitter devicecomprises a laser diode.
 31. The optical system of claim 21, wherein theat least one light-emitter device comprises a device surface in contactwith the spacer and an epitaxially-grown laser diode region located aknown distance from the device surface.
 32. The optical system of claim21, wherein the lens provides fast-axis collimation of light emitted bythe at least one light emitter device.
 33. The optical system of claim21, further comprising: a plurality of light-emitter devices disposed onthe first surface of the first substrate.
 34. The optical system ofclaim 33, wherein the spacer is in physical contact with eachlight-emitter device of the plurality of light-emitter devices.
 35. Theoptical system of claim 33, wherein the lens is optically coupled toeach light-emitter device of the plurality of light-emitter devices. 36.The optical system of claim 33, further comprising: control circuitrydisposed on the first surface of the first substrate and electricallyconnected to the plurality of light-emitter devices.
 37. The opticalsystem of claim 21, further comprising: at least one spring structuredisposed on the first surface of the first substrate, wherein the atleast one spring structure is in physical contact with the lens.
 38. Theoptical system of claim 37, wherein the at least one spring structurecomprises a wire bond.
 39. The optical system of claim 37, wherein theat least one spring structure comprises a polymer material.
 40. Theoptical system of claim 21, wherein the optical waveguide is formed froma photoresist.